Write 47 + 38 in large numerals on the IWB and give the class five seconds of quiet think-time before any hands go up. Take three or four answers and ask 'how did you do it?' rather than 'what's the answer?'. Park each method on the board without judging it; pupils will see the same answer arrive three different ways in the next step.

Walk each example one at a time. Point at the start, the arc, the landing point, and the strategy label as you say each step aloud. Pacing target: about two minutes each on Examples 1, 2 and 3, and about three minutes on Example 4 so the why-the-numbers-decide point lands properly. If you find yourself still on Example 1 after three minutes, move on — the routes repeat the same idea and each one buys back time.

• Example 1 (~2 min) — emphasise that the 38 is being broken into 30 + 8. Say: 'the tens go first, then the units come along behind.'
• Example 2 (~2 min) — make the back-jump visible by tracing under the line. Say: 'I added two too many, so I take two back.' This is where most pupils slip — they forget the take-back.
• Example 3 (~2 min) — stress why we want to land on 50: 'fifty plus anything is easier than forty-seven plus anything.'
• Example 4 (~3 min) — the punchline. Ask: 'would partitioning be sensible here?' 198 = 100 + 90 + 8 is three jumps; compensating is two. The numbers decide the strategy. Linger here — this is the moment the lesson hinges on.

This round is for talking it through together — pupils take turns at the board and the class agrees or corrects out loud.

Call up three pupils in turn — one for each strategy — so the class sees all three routes to 65. After each route lands, ask 'which strategy did you choose, and why?'

• Partition (38 + 20 = 58, 58 + 7 = 65) — most pupils' default.
• Compensate (38 + 30 = 68, 68 − 3 = 65) — listen for the size of the back-jump: it must equal the rounding-up amount.
• Bridge through 40 (38 + 2 = 40, 40 + 25 = 65) — emphasise the landing on the friendly number.

Pacing break between turns. Before calling the next pupil up, give the class a few seconds of silent think — which strategy would you reach for next, and why? — then take one pupil's answer before calling the next up.

If a pupil draws an arc that doesn't reach 65, do not correct on their behalf — ask the rest of the class to spot the error.

This round is the practice bank — pupils take turns at the board, check each answer, and the class confirms before moving on. Keep the board work brisk rather than over-explaining.

Run one round at a time. Read the first question aloud, then nominate a pupil to come to the board and type the missing number. Take the class's answer, confirm it, bank the time score, and move to the next round.

• Round 1 (bonds to 20) should be near-instant — if not, pause and rehearse the bonds-to-20 family before continuing.
• Round 4 (bonds to 1000) is where today's mental strategies start to pay off. Listen for pupils using the partition strategy out loud: '400 needs 600 more to get to 1000.'